Hydraulic valve lifter

ABSTRACT

A hydraulic valve lifter for use in a direct acting overhead camshaft valve gear of an internal combustion engine includes a body member, a plunger member located at least partially within the body member, and a face member located at least partially within the body member and having a cam engageable surface thereon. A fluid reservoir is located between the face member and the body member and a pressure chamber is disposed between the plunger member and the body member for taking up lash in the valve gear. A leakage passageway is provided between the face member and the body member and provides for the flow of lubricating fluid from the reservoir to the cam engaging surface of the face member to thereby provide for lubrication of the cam engaging surface and the cam. The leakage passageway also provides for air leakage from the lifter to prevent air lockup of the lifter.

United States Patent Abell, Jr.

HYDRAULIC VALVE LIFTER [4 Dec. 5, 1972 Primary Examiner-Laurence M.Goodridge I Assistant Examiner-Cort Flint Attorney-Teagno & Toddy [5 7]ABSTRACT A hydraulic valve lifter for use in a direct acting overheadcamshaft valve gear of an internal combustion engine includes a bodymember, a plunger member located at least partially within the bodymember, and a face member located at least partially within the bodymember and having a cam engageable surface thereon. A fluid reservoir islocated between the face member and the body member and a pressurechamber is disposed between the plunger member and the body member fortaking up lash in the valve gear. A leakage passageway is providedbetween the face member and the body member and provides for the flow oflubricating fluid from the reservoir to the cam engaging surface of theface member to thereby provide for lubrication of the cam engagingsurface and the cam. The leakage passageway also provides for airleakage from the lifter to prevent air lockup of the lifter.

10 Claims, 3 Drawing Figures PATENTEDnEc 5 I972 SHEEI 1 OF 2 ATTORNEYJFIGI HYDRAULIC VALVE LIFTER The present invention relates to a hydraulicvalve lifter for use in a direct acting overhead cam engine and moreparticularly to a hydraulic valve lifter having a leakage passagewaywhich provides for lubricant flow from the lifter to the cam engagingsurface thereof and for air flow from the lifter to prevent air lockupthereof.

During operation of an engine utilizing a direct acting overheadcamshaft valve gear and a hydraulic valve lifter for compensating forlash in the valve gear, problems occur when air in the lubricationsystem becomes internally trapped within the valve lifter. The airtrapped in the valve lifter causes air lockup which effects malfunctionof the valve lifter. This .problem of air lockup has not been solved bythe prior art lifters. Moreover, during operation of an engine in whichthe camshaft acts directly on the valve lifter it is necessary toprovide for lubrication between the camshaft and the valve lifter. Manyknown hydraulic valve lifters do not provide for adequate lubricationbetween the direct acting overhead camshaft and the valve lifter,consequently, wear and failure of the camshaft or valve lifter occurs.One known method of providing lubrication between the camshaft and thevalve gear utilizes expensive boring of the camshaft with intersectingdrilled holes in each cam lobe for directing lubrication to the lifterand camshaft. This method, used in the majority of production directacting overhead cam engines is undesirable due to the high cost involvedin drilling the camshaft and cam lobes.

Accordingly, an object of the present invention is to provide a new andimproved hydraulic valve lifter for use in a direct acting overheadcamshaft valve gear having a leakage passageway from the valve lifterfor providing for air flow from the valve lifter and/or lubricant flowfrom the valve lifter to effect lubrication of the cam member and theface surface of the valve lifter against which the cam member acts.

Another object of the present invention is to provide a new and improvedhydraulic valve lifter for use in a direct acting overhead camshaftvalve gear including a body member, a plunger member, a face memberhaving a cam engageable surface thereon, a fluid reservoir at leastpartially defined by the face member and a leakage passageway from thefluid reservoir providing for lubricant flow from the reservoir to thecam engaging surface of the face member and providing for air flow fromthe reservoir to prevent air lockup of the lifter.

Still another object of the present invention is to provide a new andimproved hydraulic valve lifter as defined in the next precedingparagraphwherein the leakage passageway is defined between the bodymember and the face member.

A further object of the present invention'is to provide a new andimproved hydraulic valve lifter including a body member, a plungermember located at least partially within the body member, a face memberslip fitted in the body member, a fluid reservoir at least partiallydefined by the face member, a leakage passageway providing for lubricantflow from the reservoir to the outer surface of the face member andproviding for air flow from the reservoir to prevent air lockup of thelifter and wherein the leakage passageway is defined between an outerperipheral surface of the face member and an inner surface of the bodymember.

A still further object of the present invention is to provide a new andimproved hydraulic valve lifter for use in a direct acting overheadcamshaft valve gear of an internal combustion engine including a bodymember, a plunger member located at least partially within the bodymember, a fluid reservoir located within the body member, a camengageable outer surface for engaging with the cam of the engine andimparting movement to the body member in response to rotation of thecam, and a leakage passageway providing for the flow of lubricatingfluid from the reservoir to the cam engageable with the surface and theflow of air from the reservoir to thereby prevent, lockup of the lifter.

Further objects and advantages of the present invention will becomeapparent from the following description taken in conjunction with theaccompanying drawings wherein:

FIG. 1 is an illustration'of a hydraulic valve lifter constructed inaccordance with the present invention, and utilized in a direct actingoverhead camshaft valve gear for operating a valve of an overhead camengine; FIG. 2-is, a sectional view, taken approximately along the'line22 of FIG. 1, illustrating the internal structure of the hydraulicvalvelifter; and

FIG. 3 is a view similar to the view of FIG. 2 illustrating the pressurechamber in an expanded condition.

The present invention relates to a hydraulic valve lifter or lashadjuster for use in a direct acting overhead camshaft valve gear, havinga leakage passageway providing for lubricant flow from the reservoir ofthe lifter to the cam engaging surface of the valve lifter. The leakagepassageway also provides for the flow of air from the valve lifter toprevent lockup thereof. The valve lifter includes a body member, aplunger member located within the body I member and cooperatingtherewith to define a pressure chamber. A face member is disposed on theupper portion of the body member and has the cam engaging surfacedisposed on the external portion thereof. The face member cooperateswith the body member to define the fluid reservoir and a passageway isprovided from the reservoir to the pressure chamber. The face member isslip fitted into the top portion of the body member and the outerperiphery of the face member cooperates with an inner surface of thebody member to define the leakage passageway which provides fluidcommunication between the reservoir and the external cam engagingsurface of the face member. The leakage passageway enables lubricant toflow from the reservoir to lubricate the cam engaging surface of theface member and provides for the flow of air from the reservoiroutwardly therefrom. The clearance between the outer periphery of theface member and the inner surface of the body member is controlled toregulate the lubricant flow from the reservoir.

Although a hydraulic lifter or lash adjuster 10 constructed inaccordance with the present invention can be used in many differenttypes of engines, the hydraulic lifter 10 is illustrated in FIG. 1 in adirect acting overhead camshaft valve gear 12 of an engine 14 having anoverhead cam 16. The valve gear 12 is actuated by rotation of the cam 16to operate a valve 20 (shown in FIG. 1 in a closed position) to controlthe flow of gases from a combustion chamber 22 in a known manner.

Means, more fully described hereinbelow, is provided to enable lubricantto flow from internal portions of the lifter 10 to effect lubrication ofthe cam 16. The means also provides for the flow of air from the lifter10 to prevent lockup of the lifter due to air becoming trappedtherein.

The cam 16 is mounted on a camshaft 24 and rotates therewith. Uponrotation of the cam 16 in a clockwise direction, a leading ramp 36 of anactuating or nose portion 38 of the cam 16 engages a face member 26 ofthe valve lifter 10 to push the valve lifter 10 and the valve 20 in adownwardly direction as viewed in FIG. 1 to open the valve 20. Continuedrotation of the cam16 brings a trailing ramp 40 of the cam 16 intoengagement with the face member 26 of the valve lifter l and the valve20 then moves toward the illustrated closed position under the influenceof a valve spring44. After a base circle portion 28 of the cam 16engages the face member 26, the valve 20 is held closed by the valvespring 44 until the leading ramp 36 of the cam 16 is again brought intoengagement with the face member 26.

The hydraulic lifter adjusts the valve gear 12 to maintain apredetermined relationship i.e.,' zero lash, between the cam 16 and thevalve even though the dimensions of the valve 20 and cam 16 may vary dueto wear, thermal effects and other reasons. To this end, the hydrauliclifter 10, as illustrated in FIG. 2, includes a generally cylindricalbody member 42 having a central chamber or cavity 46 in which a plunger48 is slidably mounted in a coaxial relationship. A snap-ring S0 isdisposed in an annular groove 52 located in the central cavity 46.

The body member 42 includes an upper cavity which is in part defined byan internal annular surface 54. The face member 26 is slip fitted in theupper cavity and an outer annular surface 56 of the face member 26 isdisposed adjacent to the annular surface 54. A shoulder 58 is providedon the body member 42 to locate the face member 26 in the upper cavity.The shoulder 58js I the passageway 66 between the fluid reservoir 60 anda discontinuous shoulder and enables fluid to flow from internalportions of the lifter between the face: member 26 and the body member42. The face member 26 cooperates with the body portion 42 to define afluid reservoir 60 in the upper cavity of the body member 42 for holdingoil or other lubricant therein. The reservoir 60 is connected in fluidcommunication with an oil pump or other source of lubricant underpressure (not shown) by a passageway 62 in the body member 42 andsuitable holes or apertures in the engine block 14 not illustrated. Thesize of reservoir 60 i.e., its depth and diameter, may be varied totailor the lifter to individual engine requirements.

A pressure chamber 64 is defined between the plunger member 48 and thebody member 42. A fluid passageway 66 is provided in the body member 42to provide for fluid communication between the reservoir 60 and thepressure chamber 64. A check valve assembly 68 cooperates with theplunger member 48 to compensate for dimensional changes in the valvegear 12 by varying the axial extent of the hydraulic lifter 10 tothereby maintain a predetermined relationship between the cam 16 andvalve 20. The check valve assembly 68 controls the flow of fluid fromthe reservoir 60 to the pressure chamber 64 by opening and closing thepressure chamber.

The check valve assembly 68 includes a check valve ball member 70, aretainer member 72 and a check valve spring 74. The retainer 72 is heldagainst the bottom surface of the body member and for illustratedpurposes is shown as having its shoulder portions '76 thereof pressfitted into an annular recess 78 in the body member 42. However,it-should be appreciated that the plunger spring 86 may be utilized tohold the retainer 72 in place. The check valve spring 74 engages withthe check valve member and the bottom portion of the retainer member 72and urges the valve member 70 into engagement with a valve seat 80disposed at one end of the passageway 66. When the check valve is in aclosed condition, as illustrated in FIG. 2, fluid flow from thereservoir 60 to the pressure chamber 64 is prevented. When the va1ve.member.70 is in an open condition, as illustrated in FIG. 3, fluid flowfrom the reservoir 60 to the pressure chamber 64 may occur. To this endthe retainer 72 includes openings 82 therein to enable fluid to flowthrough the passageway 66 through the openings 82 in the retainer 72 tothe pressure chamber 64. It should be noted that the check valveoperates as a one way valve enabling fluid to flow from the reservoir 60to the pressurechamber64. To this end the valve member 70 opens inresponse to a partial vacuum created in the pressure chamber 64 bymovement of the plunger member 48 outwardly of the body member 42 by theplunger spring 86 after the valve 20 seats to maintain zero lash in thevalve gear.

While the lifter 10 is illustrated as utilizing a check valve spring 74,the valve spring 74 may be eliminated when using the lifter with arelatively rigid valve gear of an overhead cam engine. Eliminating thecheck valve spring in a very rigid valve gear provides for a certaindegree of freedom as the normal position of the check valve when thelifter is engaged with the base circle of the cam will be opened toprovide a minor amount of movement of .the lifter due to cam bearingclearance, base circle run out and deflection of the camshaft. With nocheck valve spring the travel of the valve member 70 is limited by theretainer-72 and the check valve is closed by fluid flow when cam lift isencountered.

The fluid in the pressure chamber 64 is subjected to pressure by thedownward force of the cam 16 when the operating portion 36 thereofengages with the face member 26 of the lifter 10. Some of the fluid inthe pressure chamber 64 is forced out of the chamber along a relativelysmall clearance commonly referred to as a leak-down passageway 84disposed between the cylindrical peripheral surface of the plungermember 48 and the cylindrical inner surface of the body 42. This leakageof fluid is commonly referred to as leakdown and results in a slightinward movement of the plunger member 48 relative to the body 42 and acorresponding contraction in the pressure chamber 64. Generally, theinward movement of the plunger member 48 is on the order of 0.0Q2-0.003inches during each valve opening event. This contraction of the lifterenables the lifter to accommodate valve contraction and still maintainzero lash in the system. When the force against the outer face member 26is reduced by engagement of the base circle 28 of the cam 16 with theface member 26, a plunger spring 86 in the pressure chamber 64 biasesplunger member 48 outwardly of the body member 42 and bias the bodymember 42 upwardly to maintain the face member 26 in engagement with thecam 16. This outward movement of the plunger member 48 causes thepressure chamber 64 to expand slightly and reduces the fluid pressurewithin the chamber. Fluid pressure in the reservoir 60 is then greaterthan the fluid pressure in the chamber 64 and the valve member 70 of thecheck valve assembly 68 is moved out of engagement with the valve seat80 against the influence of the check valve spring 74 toenable fluid toflow from the reservoir 60 through the passageway 66 to the pressurechamber 64 to replace the fluid which previously leaked out of thepressure chamber.

If the effective length of the valve gear 12 should increase from onerevolution of the cam 16 to the next, the distance which the plungerspring 86 moves the plunger 48 and body 42 and the amount of replacementfluid which flows into the pressure chamber 64 is decreased to therebydecrease the effective axial length of the hydraulic lifter 10.Conversely, if the effective length of the valve gear 12 should decreasefrom one revolution of the cam member 16 to the next, the plunger spring86 moves the plunger member 48 and body member 42 outwardly to expandthe pressure chamber 64 and enables a relatively large amount ofreplacement fluid to flow into the pressure chamber 64 to thereby effectan increase in the axial length of the lifter 10. In this manner, thecheck valve assembly 68, plunger spring 86, and plunger member 48cooperate to maintain a predetermined relationship, i.e., zero lash,between the cam 16 and the valve 20 even though the effective dimensionsof the valve gear 12 change during operation of the engine 14. Ofcourse, a flat type check valve member could be used instead of the ballmember 70 which is illustrated.

The face member 26 which is slidably fitted in the upper cavity of thebody member 42 includes an outer surface 90 which is in continualengagement with the rotating cam 16. To prevent abnormal wear of thesurface 90 and the cam 16 a flow of lubricant must be provided to thesurface 90 of the face member 26. To this end, the outer peripheralsurface 56 of i the face member 26 cooperates with the inner surface 54of the body member 42 to define a leakage passageway 92 which providesfor fluid communication between the reservoir 60 and the surface 90 ofthe face member 26. The leakage passageway 92 enables fluid to flow fromthe reservoir 60, around the discontinuous shoulder portions 58, throughthe passageway 92 and to the surface 90 during normal reciprocatingmovement of the lifter 10. This flow of lubricant, which will be meteredby the cooperating surfaces 54 and 56 of the body member 42 and facemember 26 respectively, will be effectively controlled to provide forproper lubrication of the cam 16 and the surface 90 of the face member26.

The passageway 92 will also provide for the leakage of any air whichmight become trapped internally of the lifter 10. It should beappreciated that since the passageway 92 is disposed above the reservoir60 and the pressure chamber 64 any air which might become trapped in thepressure chamber 64 or the reservoir 60 will move in an upwardlydirection through the reservoir 60 to the passageway 92. The air willthen flow through the passageway 92 and out of the lifter 10. This willprevent air lockup in the lifter due to the entrapment of air in theinternal cavities therein. This is the distinct advantage over knownlifters in that aleakage passageway is provided to prevent air lockupwhich occurs when air becomes trapped in the internal cavities of thelifter 10. The entrapment of air in the pressure chambers 64 wouldeffect erratic operation of the lifter 10 since the compressibility ofair is not similar to the compressibility of the oil or lubricatingfluid which is normally disposed in the pressure chamber 64. The aboveundesirable conditions are effectively presented by the provision of thepassageway 92 which directs air from the internal parts of the lifter10. It should be appreciated that by making the face member a separatepiece complete freedom of choice in the face member material may beobtained to eliminate fabrication problems in the lifter. Specifically,the material out of which the face member 26 is constructed can be suchas to give the face surface an exceedingly hard surface for long life.Moreover, the outer diameter of the face member 26 can be controlled toprovide the proper leakage path for the lubricant flowing from thereservoir 60 to the surface 90 of the face member 26. Preferably, thecam 16 and the face member 26 have surfaces which engage to effectrotation of the face member 26 relative to the body member 42 uponreciprocation of the lifter. The rotation of face member 26 insures thatthe passageway 92 remains free of debris and does not become blocked.

From the foregoing, it should be apparent that a new and improvedhydraulic valve lifter has been provided for use in a direct actingoverhead camshaft valve gear which includes a body member, a plungermember and a face member. The face member cooperates with the bodymember to define a fluid reservoir and the plunger member cooperateswith the body member to provide a pressure chamber for adjusting theaxial extent of the lifter. The face member also cooperates with thebody member to define a leakage passageway for air which may becometrapped in the lifter. The leakage passageway enables the air to leaktherethrough so as to prevent air lockup of the lifter. Moreover, theleakage path also provides for lubricant flow from the reservoir to theface member to lubricate the cam engaging surface thereof and the cam.

I claim:

1. A hydraulic valve lifter for use in a direct acting overhead camshaftvalve gear of an internal combustion engine comprising a body member, aface member located at least in part within said body member and havinga cam engageable outer surface and an inner surface, a plunger memberlocated at least partially within said body member, a fluid chamberdefined in part by said body member for receiving lubricating fluid froma source of fluid under pressure, and a leakage passageway defined bysaid body member and said face member providing for fluid flow from saidfluid chamber to said cam engageable outer surface of said face member,said leakage passageway providing for the flow of lubricating fluid tosaid cam engageable outer surface of said face member to effectlubrication of said cam engageable outer surface and permitting air flowfrom said fluid chamber to prevent air lockup of said hydraulic valvelifter.

2. A hydraulic valve lifter for use in a direct acting overhead camshaftvalve gear of an internal combustion engine as defined in claim 1wherein said face member is slip fitted in an opening in said bodymember and said leakage passageway is defined by the outer diameter ofsaid face member and the inner diameter of said opening in said bodymember.

3. A hydraulic valve lifter for use in a direct acting overhead camshaftvalve gear of an internal combustion engine as defined in claim 1wherein said leakage passageway is defined by an outer peripheralsurface of said face member and an inner surface of said body member.

4. A hydraulic valve lifter for use in a direct acting overhead camshaftvalve gear of an internal combustion engine as defined in claim 3wherein said fluid chamber is a fluid reservoir defined by said innersurface of said face member and an internal surface 'of said bodymember.

5. A hydraulic valve lifter for-use in a direct acting overhead camshaftvalve gear of an internal combustion engine as defined in claim 4further including a pressure chamber located between said body memberand said plunger member, a fluid passageway disposed in said body memberand providing fluid communication between said fluid reservoir and saidpressure chamber, valve means for controlling the fluid flow throughsaid fluid passageway from said fluid reservoir to said pressurechamber, and a leak-down passageway defined by said plunger member andsaid body member for providing for fluid flow from said pressurechamber.

6. A hydraulic valve lifter for use in a valve gear of an internalcombustion engine comprising a body member, a plunger member located atleast partially within said body member, a face member slip fitted insaid body member, said face member having an outer cam engageablesurface, an outer peripheral surface and an inner surface, a fluidreservoir defined by said inner surface of said face member and saidbody member, a pressure chamber located between said body member andsaid plunger member, a fluid passageway located within said body memberand providing for fluid communication between said fluid reservoir andsaid pressure chamber, and a leakage passageway defined by said outerperipheral surface of said face member and said body member providingfor fluid communication between said reservoir and said outer camengageable surface of said face member, said leakage passagewayproviding fluid flow from said reservoir to said outer cam engageablesurface of said face member, said fluid flow effecting lubrication ofsaid outer cam engageable surface.

7. A hydraulic valve lifter as defined in claim 6 further includingcheck valve means disposed in said fluid passageway for controlling thefluid flow from said fluid reservoir to said pressure chamber to therebycontrol the axial extent of said hydraulic valve lifter.

8. A hydraulicvalve lifter for use in a direct acting overhead camshaftvalve gear with an internal combustion engine comprising a body member,a plunger member located at least partially within said body member, afluid reservoir disposed in said body member for receiving lubricatingfluid from a source of fluid under pressure, a face member disposed inan opening in said body member above said fluid reservoir when saidhydraulic valve lifter is in a normal operating condition, said facemember including a cam engageable surface and an outer peripheralsurface, said outer peripheral surface cooperating with said body memberopening to provide a leakage passageway providing fluid flow from saidfluid reservoir to said cam engageable outer surface.

9. A hydraulic valve lifter as defined in claim 8 further including apressure chamber defined between said body member and said plungermember, a fluid passageway disposed in said body member andcommunicating at one end thereof with said fluid reservoir and theopposite end thereof with said pressure chamber, said fluid passagewayproviding for fluid flow from said fluid reservoir to said pressurechamber, and check valve means for controlling the fluid flow throughsaid fluid passageway to thereby control the axial extent of saidlifter.

10. A hydraulic valve lifter as defined in claim 8 wherein said facemember is slip fitted in said opening in said body member.

1. A hydraulic valve lifter for use in a direct acting overhead camshaftvalve gear of an internal combustion engine comprising a body member, aface member located at least in part within said body member and havinga cam engageable outer surface and an inner surface, a plunger memberlocated at least partially within said body member, a fluid chamberdefined in part by said body member for receiving lubricating fluid froma source of fluid under pressure, and a leakage passageway defined bysaid body member and said face member providing for fluid flow from saidfluid chamber to said cam engageable outer surface of said face member,said leakage passageway providing for the flow of lubricating fluid tosaid cam engageable outer surface of said face member to effectlubrication of said cam engageable outer surface and permitting air flowfrom said fluid chamber to prevent air lockup of said hydraulic valvelifter.
 2. A hydraulic valve lifter for use in a direct acting overheadcamshaft valve gear of an internal combustion engine as defined in claim1 wherein said face member is slip fitted in an opening in said bodymember and said leakage passageway is defined by the outer diameter ofsaid face member and the inner diameter of said opening in said bodymember.
 3. A hydraulic valve lifter for use in a direct acting overheadcamshaft valve gear of an internal combustion engine as defined in claim1 wherein said leakage passageway is defined by an outer peripheralsurface of said face member and an inner surface of said body member. 4.A hydraulic valve lifter for use in a direct acting overhead camshaftvalve gear of an internal combustion engine as defined in claim 3wherein said fluid chamber is a fluid reservoir defined by said innersurface of said face member and an internal surface of said body member.5. A hydraulic valve lifter for use in a direct acting overhead camshaftvalve gear of an internal combustion engine as defined in claim 4further including a pressure chamber located between said body memberand said plunger member, a fluid passageway disposed in said body memberand providing fluid communication between said fluid reservoir and saidpressure chamber, valve means for controlling the fluid flow throughsaid fluid passageway from said fluid reservoir to said pressurechamber, and a leak-down passageway defined by said plunger member andsaid body member for providing for fluid flow from said pressurechamber.
 6. A hydraulic valve lifter for use in a valve gear of aninternal combustion engine comprising a body member, a plunger memberlocated at least partially within said body member, a face member slipfitted in said body member, said face member having an outer camengageable surface, an outer peripheral surface and an inner surface, afluid reservoir defined by said inner surface of said face member andsaid body member, a pressure chamber located between said body memberand said plunger member, a fluid passageway located within said bodymember and providing for fluid communication between said fluidreservoir and said pressure chamber, and a leakage passageway defined bysaid outer peripheral surface of said face member and said body memberproviding for fluid communication between said reservoir and said outercam engageable surface of said face member, said leakage passagewayproviding fluid flow from said reservoir to said outer cam engageablesurface of said face member, said fluid flow effecting lubrication ofsaid outer cam engageable surface.
 7. A hydraulic valve lifter asdefined in claim 6 further including check valve means disposed in saidfluid passageway for controlling the fluid flow from said fluidreservoir to said pressure chamber to thereby control the axial extentof said hydraulic valve lifter.
 8. A hydraulic valve lifter for use in adirect acting overhead camshaft valve gear with an internal combustionengine comprising a body member, a plunger member located at leastpartially within said body member, a fluid reservoir disposed in saidbody member for receiving lubricating fluid from a source of fluid underpressure, a face member disposed in an opening in said body member abovesaid fluid reservoir when said hydraulic valve lifter is in a normaloperating condition, said face member including a cam engageable surfaceand an outer peripheral surface, said outer peripheral surfacecooperating with said body member opening to provide a leakagepassageway providing fluid flow from said fluid reservoir to said camengageable outer surface.
 9. A hydraulic valve lifter as defined inclaim 8 further including a pressure chamber defined between said bodymember and said plunger member, a fluid passageway disposed in said bodymember and communicating at one end thereof with said fluid reservoirand the opposite end thereof with said pressure chamber, said fluidpassageway providing for fluid flow from said fluid reservoir to saidpressure chamber, and check valve means for controlling the fluid flowthrough said fluid passageway to thereby control the axial extent ofsaid lifter.
 10. A hydraulic valve lifter as defined in claim 8 whereinsaid face member is slip fitted in said opening in said body member.